Insights on Potential Formation Damage Mechanisms Associated with Hydraulic Fracturing

Abstract

AbstractHydraulic fracturing technique, using water-soluble polymers, has been extensively used to improve the productivity of oil and gas wells, especially in low-permeability formations. However, the production enhancement by hydraulic fracturing can be hindered by the fracture conductivity damage and/or fracture face skin. This paper describes an approach to establish a suitable fracturing fluid cleanup process by analyzing the performance of different gel breaker types, especially in sours environments. In addition, the interaction of clay stabilizers with different gel breakers is investigated.Several experiments were conducted to assess the effect of different gel breakers on high temperature fracturing fluid as a function of time. Most commonly used breakers- inorganic oxidizers (bromate and persulfate salts), specific enzymes and acids- were used in this evaluation. The effectiveness of each breaker was evaluated using various techniques, such as Zeta Potential, Gel Permeation Chromatography (GPC), High-Pressure/High-Temperature (HP/HT) aging cells, H2S compatibility tests and Environmental Scanning Electron Microscope (ESEM). All experiments were performed on borate and zirconate crosslinked carboxymethyl-hydroxypropyl guar (CMHPG) guar gum system with loading up to 45 lb/1,000 gals in addition to clay control agents potassium chloride and polymer-based clay stabilizers.The results obtained from this study have shown that amount and size of the residual gel polymer chains, after its breakage, were mainly dependent on the type and loading of used gel breaker. Furthermore, it was found that both KCl and polymer-based clay stabilizers were effective in preventing clay-induced formation damage. However, laboratory tests have revealed that some gel breaker types may negatively affect the performance of polymer-based clay stabilizers. Additionally, this paper will highlight other negative interactions of common gel breakers, especially in sour environments.